There has been a lot of excitement this spring around the biggest flat fish in the Gulf of Maine. Atlantic halibut—Hippoglossus hippoglossus—is a large, right-eyed flounder found between New York and Labrador. The largest halibut ever recorded was 620 pounds off of Cape Ann, and a 250-pound fish was landed in Bass Harbor last year.

Halibut, like many of the delicious fish and shellfish native to our region, have had a checkered past.

During New England’s fishing heyday in the 1700s and 1800s, halibut was considered a nuisance species that got in the way of fishermen targeting cod. By the mid 1800s, fishermen began targeting halibut, quickly leading to declines and an eventual population crash, from which the species has yet to fully recover.

The past decade has shown promising signs, but slow growth and late maturity create a challenge for rebuilding the population. Halibut now supports a small, but important fishery, providing supplemental income to Maine fishermen during the spring.

Halibut weren’t federally managed in the U.S. until 1999, and Maine’s first regulations came around the same time. In 2004, NOAA fisheries identified Atlantic halibut as a “species of concern” and the fishery now operates under strict catch limits and an annual total allowable catch. Fishermen can only keep a total of 25 fish each year, with a minimum size of 41 inches, and the fishery is constrained to May and June.

In Maine state waters the fishery is hook-only, and most of the participants are lobstermen who set a long-line of hooks along the seafloor, or hooks attached to lobster traps, at the beginning of their day, and then return to retrieve their halibut hooks after a day of lobster fishing. At 20-plus pounds each, and a sale price of $5 or more per pound at the dock, a single halibut can more than cover the cost of fuel and bait for a day of lobster fishing.

Sometimes fishermen will sell the body and keep the head for the cheek meat, considered a delicacy to the old timers. The head and racks (skeletons) can also be used for lobster bait.

Very few halibut are sampled in the Maine Department of Marine Resource’s annual scientific trawl survey, probably because the adults are fast swimmers and so can avoid trawl nets. This, combined with the small commercial catch, has led to an extreme lack of data about the population. The scientific literature also is thin on Atlantic halibut, but fishermen know a lot about them.

Julia Beaty, a recent graduate of the University of Maine’s dual masters degree program in marine biology and marine policy, studied growth rates and habitat preferences of halibut and interviewed 25 halibut fishermen to learn about how halibut interact with their environment. She developed a mathematical model to inform fisheries managers about habitat requirements of halibut.

“In the end,” Beaty said, “I learned a lot more about halibut from the fishermen.” Beaty reported that a lot of what she learned from fishermen was different than what appeared in some of the older literature. For instance, fishermen today are finding lobsters and crabs in the stomachs of large halibut, whereas the literature pointed to halibut switching from an invertebrate diet to a fish diet as they grew.

Beaty stressed the importance of this fishery to the fishermen she interviewed. She also explained how the size of the hooks are designed to target a specific size range of fish, leaving both the smaller and larger fish in the water in order to protect juveniles and the breeding population. The largest fish produce many more young than newly-reproductive fish, so there is an important conservation benefit to leaving them in the water.

Also, surveys have documented that 75 percent of the fish that are caught at less than the required 41 inches survive upon release. In Canada, they have a smaller minimum size, but have been certified as sustainable by the Marine Stewardship Council (MSC), opening up the door for Maine to pursue this certification as well.

Beaty pointed out that her interviews were about habitat preferences of halibut, not changes in abundance.

“Yet almost every fisherman wanted to talk about the fact that they are seeing a lot more juvenile halibut in the water,” she said, “and this year, more seem to be of legal size than in past years.”

So, while halibut are definitely not out of the woods, there are encouraging signs. With some other fisheries in Maine suffering, halibut may be a bright spot in fishermen’s ability to diversify their harvest in future years.

Dr. Heather Deese is an oceanographer and the Island Institute’s vice-president for strategic development. Dr. Susie Arnold is an ecologist and marine scientist with the organization.